In the wireless communication technology, when the base station side (for example the evolved node B, that is eNB) transmits data by using the a plurality of antennas, the way of the spatial multiplexing can be taken to improve the data transmission rate, that is, the sending end transmits different data in different antenna locations by using the same time-frequency resources, and the receiving end (such as the user equipment, UE) also receives the data by using a plurality of antennae. The resources of all antennae are distributed to the same one user in the case of single user, and that user individually occupies the physical resource assigned by the base station side within one transmission interval, and this transmission way is called as the Single User Multiple-Input Multiple-Output (abbreviated as SU-MIMO); the space resources of different antennae are distributed to different users in the case of multi-user, one user and at least one other user share the physical resource assigned by the base station side within one transmission interval, where the share mode can be a space division multiple access way or space division multiplexing way, and this transmission way is called as the Multiple User Multiple-Input Multiple-Output (abbreviated as MU-MIMO), wherein, the physical resources assigned by the base station side refers to the time-frequency resource. If the transmission system needs to support the SU-MIMO and the MU-MIMO at the same time, then the eNB needs to provide the data under these two modes to the UE. The UE needs to acquire the rank used by the eNB transmitting the MIMO data to the UE no matter in the SU-MIMO mode or the MU-MIMO mode. Under the SU-MIMO mode, the resources of all antennae are distributed to the same one user, the number of the layers used for transmitting the MIMO data equals the rank used by the eNB transmitting the MIMO data; under the MU-MIMO mode, the number of the layers used during the transmission corresponding to one user is less than the total number of the layers used by the eNB transmitting the MIMO data, and if the switch between the SU-MIMO mode and the MU-MIMO is required, then the eNB needs to notify different control data to the UE under different transmission modes.
The standard of the Long-Term Evolution (abbreviated as LTE) release 8 defines the following three kinds of downlink physical control channels: the Physical Control Format Indicator Channel (abbreviated as PCFICH), the Physical Hybrid Automatic Retransmission Request Indicator Channel (abbreviated as PHICH) and the Physical Downlink Control Channel (abbreviated as PDCCH). Wherein, the PDCCH is used for bearing the Downlink Control Information (abbreviated as DCI), including: the uplink and downlink scheduling information, and the uplink power control information. The DCI format is divided into the following kinds: DCI format 0, DCI format 1, DCI format 1A, DCI format 1B, DCI format 1C, DCI format 1D, DCI format 2, DCI format 2A, DCI format 3 and DCI format 3A, etc.; wherein, the transmission mode 5 which supports the MU-MIMO utilizes the downlink control information of the DCI format 1D, and the downlink power offset field δpower-offset in the DCI format 1D is used to indicate the information of reducing the power of one user by half (that is, −10 log 10 (2)) in the MU-MIMO mode. Since the MU-MIMO transmission mode 5 only supports the MU-MIMO transmission of two users, through this downlink power offset field, the MU-MIMO transmission mode 5 can support the dynamic switch between the SU-MIMO mode and the MU-MIMO mode, however, the DCI format only supports the transmission of one stream for one UE no matter in the SU-MIMO mode or the MU-MIMO mode. Although the LTE Release 8 supports the single user transmission of at most two streams in the transmission mode 4, since the switch between the transmission modes can only be half static, it cannot perform the dynamic switch between the single user multi-stream transmission and the multi-user transmission in LTE release 8.
In the release 9 of the LTE, in order to enhance the downlink multi-antenna transmission, the transmission mode of the dual-stream Beamforming is introduced, and the downlink control information is increased with DCI format 2B to support the transmission mode. There is one identification bit of the scrambling identity (abbreviated in as SCID) in the DCI format 2B to support two different scrambling sequences, and the eNB can distribute these two scrambling sequences to different users and multiplex a plurality of users in the same one resource. In addition, when only one transport block is enabled, the new data identification (NDI) bit corresponding to the disabled transport block is also used to indicate the antenna port in the single-layer transmission.
In addition, in the release 10 of the LTE, the transmission mode of the MIMO has already confirmed that the Demodulation Reference Signal (abbreviated as DMRS) is used as the pilot frequency for the demodulation, and the UE needs to obtain the position of the pilot frequency and then can perform the estimation of the channel and the interference on the pilot frequency. The number of the total layers of different transmission has different pilot frequency patterns, for example, three different patterns are preliminarily defined in the release 10 of the LTE. When the number of the total layers of the transmission or the rank is 1 or 2, the first pattern (DMRS pattern 1) is used; when the number of the total layers of the transmission or the rank is 3 or 4, the second pattern (DMRS pattern 2) is used; when the number of the total layers of the transmission or the rank is any value from 5 to 8, the third pattern (DMRS pattern 3) is used. In the SU-MIMO mode, the data in all transmission layers are sent to the same one UE, so the UE can know the pattern of the pilot frequency and can know the pilot frequency position only if it obtains the rank. In the MU-MIMO mode, the UE needs to acquire the rank and the number of the layers starting to perform the transmission to the UE, and the UE also needs to acquire the pilot frequency pattern for transmission then it can only obtain the pilot frequency position. In addition, different DMRS ports use different spreading codes, and the UE further needs to acquire the spreading code used for transmission and then can only obtain the information on the pilot frequency. In the technology of the existing LTE release number 10, the above-mentioned demand is not supported. In the LTE release 10, it is already confirmed that the transmission mode of the MIMO is required to support single user transmission of which the maximum number of the total layers is 8, and support the single user and multi-user transmission in the same one transmission mode, however, signaling of the MIMO multi-user transmission based on the DMRS has not been supported yet.